Endocrine Disrupting Chemicals 2012 - World Health Organization

evealed the complex interactions of some chemicals
with endocrine systems, which may escape detection
in current validated test systems. Finally, it will be
important to develop weight-of-evidence approaches
that allow effective consideration of research from
all levels—from in vitro mechanistic data to human
epidemiological data.
C. Reducing exposures and thereby vulnerability
to disease: It is imperative that we know the nature
of EDCs to which humans and wildlife are exposed,
together with information about their concentrations
in blood, placenta, amniotic fluid and other tissues,
across lifespans, sexes, ethnicities (or species of wildlife)
and regions. Many information gaps currently exist
with regard to what is found in human and wildlife
tissues, more so for developing countries and countries
with economies in transition and for chemicals that are
less bioaccumulative in the body. Long-term records to
help us understand changes in exposures exist only for
POPs and only for a few countries.
In addition, there is a need to continue expanding
the list of chemicals currently examined to include
those contained in materials and goods as well as
chemical by-products; it is impossible to assess
exposure without knowing the chemicals to target.
The comprehensive measurement of all exposure
events during a lifetime is needed, as opposed to
biomonitoring at specific time points, and this
requires longitudinal sampling, particularly during
critical life stages, such as fetal development, early
childhood and the reproductive years.
Wildlife and humans are exposed to a wide variety
of EDCs that differ greatly in their physical and
chemical properties. Further, these compounds
are generally present at trace concentrations and
in complex matrices requiring highly selective and
sensitive analytical methods for their measurement.
The wide range of different compound classes
requires a variety of analytical approaches and
techniques, making it challenging to understand all
of the different chemicals in the environment and in
human and wildlife tissues. There is a growing need
to develop new analytical techniques and approaches
to prioritize the assessment of EDCs. There is global
transport of EDCs through natural processes (ocean
and air currents) as well as commerce, leading to
worldwide exposures. New sources of exposure
to EDCs, in addition to food, have been identified
and include indoor environments and electronics
recycling and dumpsites (of particular concern in
developing countries and countries with economies
in transition). The sources and routes of exposure to
EDCs need to be further investigated.
D. Identifying endocrine active chemicals: Identifying
chemicals with endocrine disrupting potential among
all of the chemicals used and released worldwide is a
major challenge, and it is likely that we are currently
assessing only the “tip of the iceberg”. It is possible to
trace high production volume chemicals, but that is
not the case for the numerous additives and process
chemicals. Adding greatly to the complexity, and to
the number of chemicals in our environment, are the
unknown or unintended by-products that are formed
during chemical manufacturing, during combustion
processes and via environmental transformations.
While the active ingredients in pharmaceuticals
and pesticides have to be documented on the final
product, this is not the case for chemicals in articles,
materials and goods. Personal hygiene products and
cosmetics require declarations of the ingredients, and
the number of chemicals applied in this sphere of uses
counts in the thousands. Many sources of EDCs are
not known because of a lack of chemical constituent
declarations in products, materials and goods. We
need to know where the exposures are coming from.
E. Creating enabling environments for scientific
advances, innovation and disease prevention:
Exposure to EDCs and their effects on human and
wildlife health are a global problem that will require
global solutions. More programmes are needed that
foster collaboration and data sharing among scientists
and between governmental agencies and countries.
To protect human health from the combined effects
of exposures to EDCs, poor nutrition and poor living
conditions, there is a need to develop programmes
and collaborations among developed and developing
countries and those in economic transition. There
is also a need to stimulate new adaptive approaches
that break down institutional and traditional
scientific barriers and stimulate interdisciplinary and
multidisciplinary team science.
F. Methods for evaluating evidence: There is currently
no widely agreed system for evaluating the strength
of evidence of associations between exposures to
chemicals (including EDCs) and adverse health
outcomes. A transparent methodology is also
missing. The need for developing better approaches
for evaluating the strength of evidence, together
with improved methods of risk assessment, is widely
recognized. Methods for synthesizing the science
into evidence-based decisions have been developed
and validated in clinical arenas. However, due to
differences between environmental and clinical health
sciences, the evidence base and decision context of
these methods are not applicable to exposures to
environmental contaminants, including EDCs. To
meet this challenge, it will be necessary to exploit new
methodological approaches. It is essential to evaluate
associations between EDC exposures and health
outcomes by further developing methods for which
proof of concept is currently under development.
28 State of the Science of Endocrine Disrupting Chemicals – 2012